From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/fs/btrfs/struct-funcs.c | 206 ++++++++++++++++++++++++++++++--------------------
1 files changed, 123 insertions(+), 83 deletions(-)
diff --git a/kernel/fs/btrfs/struct-funcs.c b/kernel/fs/btrfs/struct-funcs.c
index 4c13b73..c46be27 100644
--- a/kernel/fs/btrfs/struct-funcs.c
+++ b/kernel/fs/btrfs/struct-funcs.c
@@ -7,112 +7,152 @@
#include "ctree.h"
-static inline u8 get_unaligned_le8(const void *p)
+static bool check_setget_bounds(const struct extent_buffer *eb,
+ const void *ptr, unsigned off, int size)
{
- return *(u8 *)p;
-}
+ const unsigned long member_offset = (unsigned long)ptr + off;
-static inline void put_unaligned_le8(u8 val, void *p)
-{
- *(u8 *)p = val;
+ if (member_offset > eb->len) {
+ btrfs_warn(eb->fs_info,
+ "bad eb member start: ptr 0x%lx start %llu member offset %lu size %d",
+ (unsigned long)ptr, eb->start, member_offset, size);
+ return false;
+ }
+ if (member_offset + size > eb->len) {
+ btrfs_warn(eb->fs_info,
+ "bad eb member end: ptr 0x%lx start %llu member offset %lu size %d",
+ (unsigned long)ptr, eb->start, member_offset, size);
+ return false;
+ }
+
+ return true;
}
/*
- * this is some deeply nasty code.
+ * Macro templates that define helpers to read/write extent buffer data of a
+ * given size, that are also used via ctree.h for access to item members by
+ * specialized helpers.
*
- * The end result is that anyone who #includes ctree.h gets a
- * declaration for the btrfs_set_foo functions and btrfs_foo functions,
- * which are wrappers of btrfs_set_token_#bits functions and
- * btrfs_get_token_#bits functions, which are defined in this file.
+ * Generic helpers:
+ * - btrfs_set_8 (for 8/16/32/64)
+ * - btrfs_get_8 (for 8/16/32/64)
*
- * These setget functions do all the extent_buffer related mapping
- * required to efficiently read and write specific fields in the extent
- * buffers. Every pointer to metadata items in btrfs is really just
- * an unsigned long offset into the extent buffer which has been
- * cast to a specific type. This gives us all the gcc type checking.
+ * Generic helpers with a token (cached address of the most recently accessed
+ * page):
+ * - btrfs_set_token_8 (for 8/16/32/64)
+ * - btrfs_get_token_8 (for 8/16/32/64)
*
- * The extent buffer api is used to do the page spanning work required to
- * have a metadata blocksize different from the page size.
+ * The set/get functions handle data spanning two pages transparently, in case
+ * metadata block size is larger than page. Every pointer to metadata items is
+ * an offset into the extent buffer page array, cast to a specific type. This
+ * gives us all the type checking.
+ *
+ * The extent buffer pages stored in the array pages do not form a contiguous
+ * phyusical range, but the API functions assume the linear offset to the range
+ * from 0 to metadata node size.
*/
#define DEFINE_BTRFS_SETGET_BITS(bits) \
-u##bits btrfs_get_token_##bits(const struct extent_buffer *eb, \
- const void *ptr, unsigned long off, \
- struct btrfs_map_token *token) \
+u##bits btrfs_get_token_##bits(struct btrfs_map_token *token, \
+ const void *ptr, unsigned long off) \
{ \
- unsigned long part_offset = (unsigned long)ptr; \
- unsigned long offset = part_offset + off; \
- void *p; \
- int err; \
- char *kaddr; \
- unsigned long map_start; \
- unsigned long map_len; \
- int size = sizeof(u##bits); \
- u##bits res; \
+ const unsigned long member_offset = (unsigned long)ptr + off; \
+ const unsigned long idx = member_offset >> PAGE_SHIFT; \
+ const unsigned long oip = offset_in_page(member_offset); \
+ const int size = sizeof(u##bits); \
+ u8 lebytes[sizeof(u##bits)]; \
+ const int part = PAGE_SIZE - oip; \
\
- if (token && token->kaddr && token->offset <= offset && \
- token->eb == eb && \
- (token->offset + PAGE_SIZE >= offset + size)) { \
- kaddr = token->kaddr; \
- p = kaddr + part_offset - token->offset; \
- res = get_unaligned_le##bits(p + off); \
- return res; \
+ ASSERT(token); \
+ ASSERT(token->kaddr); \
+ ASSERT(check_setget_bounds(token->eb, ptr, off, size)); \
+ if (token->offset <= member_offset && \
+ member_offset + size <= token->offset + PAGE_SIZE) { \
+ return get_unaligned_le##bits(token->kaddr + oip); \
} \
- err = map_private_extent_buffer(eb, offset, size, \
- &kaddr, &map_start, &map_len); \
- if (err) { \
- __le##bits leres; \
+ token->kaddr = page_address(token->eb->pages[idx]); \
+ token->offset = idx << PAGE_SHIFT; \
+ if (oip + size <= PAGE_SIZE) \
+ return get_unaligned_le##bits(token->kaddr + oip); \
\
- read_extent_buffer(eb, &leres, offset, size); \
- return le##bits##_to_cpu(leres); \
- } \
- p = kaddr + part_offset - map_start; \
- res = get_unaligned_le##bits(p + off); \
- if (token) { \
- token->kaddr = kaddr; \
- token->offset = map_start; \
- token->eb = eb; \
- } \
- return res; \
+ memcpy(lebytes, token->kaddr + oip, part); \
+ token->kaddr = page_address(token->eb->pages[idx + 1]); \
+ token->offset = (idx + 1) << PAGE_SHIFT; \
+ memcpy(lebytes + part, token->kaddr, size - part); \
+ return get_unaligned_le##bits(lebytes); \
} \
-void btrfs_set_token_##bits(struct extent_buffer *eb, \
- const void *ptr, unsigned long off, \
- u##bits val, \
- struct btrfs_map_token *token) \
+u##bits btrfs_get_##bits(const struct extent_buffer *eb, \
+ const void *ptr, unsigned long off) \
{ \
- unsigned long part_offset = (unsigned long)ptr; \
- unsigned long offset = part_offset + off; \
- void *p; \
- int err; \
- char *kaddr; \
- unsigned long map_start; \
- unsigned long map_len; \
- int size = sizeof(u##bits); \
+ const unsigned long member_offset = (unsigned long)ptr + off; \
+ const unsigned long oip = offset_in_page(member_offset); \
+ const unsigned long idx = member_offset >> PAGE_SHIFT; \
+ char *kaddr = page_address(eb->pages[idx]); \
+ const int size = sizeof(u##bits); \
+ const int part = PAGE_SIZE - oip; \
+ u8 lebytes[sizeof(u##bits)]; \
\
- if (token && token->kaddr && token->offset <= offset && \
- token->eb == eb && \
- (token->offset + PAGE_SIZE >= offset + size)) { \
- kaddr = token->kaddr; \
- p = kaddr + part_offset - token->offset; \
- put_unaligned_le##bits(val, p + off); \
+ ASSERT(check_setget_bounds(eb, ptr, off, size)); \
+ if (oip + size <= PAGE_SIZE) \
+ return get_unaligned_le##bits(kaddr + oip); \
+ \
+ memcpy(lebytes, kaddr + oip, part); \
+ kaddr = page_address(eb->pages[idx + 1]); \
+ memcpy(lebytes + part, kaddr, size - part); \
+ return get_unaligned_le##bits(lebytes); \
+} \
+void btrfs_set_token_##bits(struct btrfs_map_token *token, \
+ const void *ptr, unsigned long off, \
+ u##bits val) \
+{ \
+ const unsigned long member_offset = (unsigned long)ptr + off; \
+ const unsigned long idx = member_offset >> PAGE_SHIFT; \
+ const unsigned long oip = offset_in_page(member_offset); \
+ const int size = sizeof(u##bits); \
+ u8 lebytes[sizeof(u##bits)]; \
+ const int part = PAGE_SIZE - oip; \
+ \
+ ASSERT(token); \
+ ASSERT(token->kaddr); \
+ ASSERT(check_setget_bounds(token->eb, ptr, off, size)); \
+ if (token->offset <= member_offset && \
+ member_offset + size <= token->offset + PAGE_SIZE) { \
+ put_unaligned_le##bits(val, token->kaddr + oip); \
return; \
} \
- err = map_private_extent_buffer(eb, offset, size, \
- &kaddr, &map_start, &map_len); \
- if (err) { \
- __le##bits val2; \
- \
- val2 = cpu_to_le##bits(val); \
- write_extent_buffer(eb, &val2, offset, size); \
+ token->kaddr = page_address(token->eb->pages[idx]); \
+ token->offset = idx << PAGE_SHIFT; \
+ if (oip + size <= PAGE_SIZE) { \
+ put_unaligned_le##bits(val, token->kaddr + oip); \
return; \
} \
- p = kaddr + part_offset - map_start; \
- put_unaligned_le##bits(val, p + off); \
- if (token) { \
- token->kaddr = kaddr; \
- token->offset = map_start; \
- token->eb = eb; \
+ put_unaligned_le##bits(val, lebytes); \
+ memcpy(token->kaddr + oip, lebytes, part); \
+ token->kaddr = page_address(token->eb->pages[idx + 1]); \
+ token->offset = (idx + 1) << PAGE_SHIFT; \
+ memcpy(token->kaddr, lebytes + part, size - part); \
+} \
+void btrfs_set_##bits(const struct extent_buffer *eb, void *ptr, \
+ unsigned long off, u##bits val) \
+{ \
+ const unsigned long member_offset = (unsigned long)ptr + off; \
+ const unsigned long oip = offset_in_page(member_offset); \
+ const unsigned long idx = member_offset >> PAGE_SHIFT; \
+ char *kaddr = page_address(eb->pages[idx]); \
+ const int size = sizeof(u##bits); \
+ const int part = PAGE_SIZE - oip; \
+ u8 lebytes[sizeof(u##bits)]; \
+ \
+ ASSERT(check_setget_bounds(eb, ptr, off, size)); \
+ if (oip + size <= PAGE_SIZE) { \
+ put_unaligned_le##bits(val, kaddr + oip); \
+ return; \
} \
+ \
+ put_unaligned_le##bits(val, lebytes); \
+ memcpy(kaddr + oip, lebytes, part); \
+ kaddr = page_address(eb->pages[idx + 1]); \
+ memcpy(kaddr, lebytes + part, size - part); \
}
DEFINE_BTRFS_SETGET_BITS(8)
--
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